Recombinant Anti-CD28 x Anti-HN Bispecific Antibody (Bibody) is a Fab-scFv format that uses heterodimeric Fab as a scaffold, and a scFv region linked to one of its heavy (Fd) or light (L) chain. The scFv of the anti-CD28 specificity is fused to the anti-CD28 heavy or light chain of the Fab. This BsAb can retarget T cells to tumor cells. It is designed for the tumor vaccine modification and the research of Tumors therapy.